1. Observation of Prompt Energization to ultra relativistic energies by the March 2015 interplanetary shock Shri Kanekal, Dan Baker, Bern Blake, Sam Califf, Seth Claudepierre, Scot Elkington, Joe Fennell, Allison Jaynes, Ashley Jones, Craig Kletzing, Xinlin Li, Geoff Reeves, Harlan Spence, and Lynn Wilson

2. WIND, SOHO IP Shock observations

3. Prompt electron response: REPT A ultra relativistic electrons Post injection velocity dispersion

4. REPT A observations continued  Electrons energized to ultra-relativistic energies (>6 MeV)  Clear velocity dispersion suggesting local injection

5. MagEIS A observations  Weak enhancement in low energy channels - likely bremsstrahlung background  Implies energization confined to 1.0 to 6.0 MeV Joe Fennell, Seth ClaudePierre

6. REPT and MagEIS post shock pitch angle distributions Probe B Seth ClaudePierre

7. Shock Injection and velocity dispersion Xinlin Li

8. E and B Fields data from EFW and EMFISIS Sam Califf

9. Drift velocity for electrons in a dipole field

10. Ground magnetometer observations 210 Chain KAG Joe Fennell, Bern Blake Time of shock passage 04:45 UT

11. Shock Analysis based upon WIND measurements Shock normal angle [degrees]: 56.1 ± 6.5 Sound speed Mach number: 6.74 ± 0.51 Alfven Mach number: 4.24 ± 0.42 Fast mode Mach number: 3.69 ± 0.21 Shock density compression ratio: 2.16 ± 0.39 Shock normal vector [GSE]: (-0.714814, -0.385614, 0.552736) Upstream shock normal speed [spacecraft frame]: 510.79 km/s Wind was located at the shock arrival time (~04:00 UT at Wind) at roughly: (1612674.625, 346568.312, 80152.977) [km, GSE] Lynn Wilson

12. Peak flux times and drift speed E (MeV) Vd (Rads/min) Time (hr:min:sec) T Mins. Of day ϕ0ϕ0 6.31.5724:47:28287.470.461 5.21.3374:47:43287.650.464 4.21.0974:48:00287.830.467 3.40.9064:48:27288.380.471 2.60.7134:48:47288.730.475

13. Drift Period Analysis from REPT A Time injection = 286.2 ± 0.3 ϕ injection = -1.50 ± 0.15 = 274.0 0 ± 9 0 ϕ s/c = 0.47 rad. = 27 0

14. Shock arrival calculated from WIND compared to injection time from REPT observations Assume Nominal Magnetopause at 11Re, i.e. 70125 km Distance in X (GSE) travelled by shock ΔX = X Wind -X MP = 1612674 - 70125 = 1542549 km Time of traversal = 1542549*0.88/510 where 0.88 is cosine of shock normal angle θ Time of traversal = 2661 sec = 44min Time of shock at WIND = 4:00UT propagated time to MP nose = 4:44UT from REPT measurements = 4.46UT

15.  Shock response of electrons show several interesting features - prompt injection of ~1 to 6 MeV electrons - no discernible response of ~200 keV to ~1 MeV  Ground level discontinuity 04:45 UT (shock passage) - Estimated time of injection 04:46:18 UT - Electrons energized to 6 MeV in < 2 minutes  Drift echo times consistent with expectation [O’Brien et al.,2015]  Detailed analyses underway - multiple publications planned - encourage participation from SWG Summary and Conclusions

16. Shock Arrival calculated from WIND position and shock measurements Vdt dx -y GSE -x GSE Shock front Shock normal θ Vdt/dx = cosθ => dt = dx*cosθ/V

18. Drift Period Analysis from REPT A Time injection = 286.3 ± 0.3 ϕ injection = -0.47 ± 0.15 = 333.1 0 ± 9 0 ϕ s/c = 0.47 rad. = 27 0

19. 4:48:442.6 MeV 4:48:23 3.4 MeV 4:47:5 0 4.2 MeV 4:47:3 9 5.2 MeV REPT A flux profiles 90 0 pitch angle Ashley Jones